Dr. martin Lotz from the University of Greifswald in Germany have used functional magnetic resonance (fMIR) scanners to get a sneak peek of what happens in the brains of professional and non-experienced writers when they are working on a story.
Long story short, once you start writing, your brain activates hippocampus, visual cortex among many regions in the brain, the former is activated when one tries to remember info, the latter activates when one starts engaging his imagination...and they all interacts together causing multiplying in the connections between neurons.
Moreover, since the visual cortex is activated and you start imagining what you want, your body starts giving you the motivation hormone dopamine, which keeps you focused on what you locked your vision on. The mind have thusands of thoughts a day, out of which the brain doesnt know which to give priority and which to accomplish, so by writing the goals down you focus your mind on the toughts you want him to start processing.
Allan pease also talks about how hand writing generates many connections between neurons even much more than the connections generated when you write on a keyboard. He says also about how you become emotionally involved as well.
The best example is when you start your day by writing "to-do" list, and note how you get focused by giving the right priority to the right task.
So he bottom line, writing your goals isnt a abas idea...start a draft today and let us see how it goes.